The progress of solid state devices has allowed fabrication of micro and nano-scale electronic devices for a wide range of applications. Most conventional electronic devices are fabricated in silicon, germanium or some other semi-conductor material. Metallic electrical contacts are generally used to interface such micro and nano-scale electronic devices with macro electronics. The metallic contact pads are susceptible to corrosion so noble metals such as platinum and gold are often used to form the electrical contacts which increase the cost of such electronic devices.
X-ray monitors are a class of electronic devices that are used to monitor position of X-ray beams, flux and timing of X-ray beams. Such X-ray beams can be included in synchrotron radiation which is defined as an electromagnetic wave radiated in a direction tangent to an orbit of an electron having been accelerated by an electron accelerator. Synchrotron radiation can include light wavelengths ranging from visible light to hard X-rays and can be used to perform spectroscopy and diffraction experiments. To perform such experiments, the X-ray beam monitors are necessary to monitor and stabilize X-ray beams.
Conventional X-ray monitors are formed from semi-conductor materials such as silicon and germanium. Such devices generally include a p-n junction formed in the semiconductor material. When X-ray beams are injected into the p-n junction, electron-hole pairs are generated which produce current. However, such semi-conductor devices have a smaller response speed due to small saturated velocity of carriers because of the electric properties of silicon or germanium. For example, silicon has a resistivity of 105 Ohm-cm and germanium has low resistivity. Furthermore, such detectors produce excessive dark current.
In contrast, diamond is particularly attractive for fabricating X-ray monitors to measure flux, position and timing of monochromatic and white X-ray beam. Diamond, because of its low Z (atomic number), has lower absorption for X-rays, extreme resistance to corrosion and radiation damage, high thermal conductivity and the ability to operate at high temperatures with low leakage. A voltage is applied to an intrinsic region of such diamond based X-ray monitors which acts as an active element obviating the need for a p-n junction. This is because diamond has sufficiently high resistivity in its intrinsic region. Therefore, electron-hole pairs are generated in the entire region of the diamond through which X-ray beams pass.
Conventional diamond based X-ray monitors, however include metal electrical contacts. Since metals have high atomic number (Z), the metal electrical contacts absorb a significantly higher amount of X-rays relative to the diamond thereby, drastically reducing the efficiency of such diamond detectors.